Introduction: Hyponatremia predicts adverse prognosis in patients with heart failure in particular with reduced ejection fraction. In contrast, it has recently been reported that hyponatremia on admission is not a predictor of post-discharge mortality in patients with heart failure with preserved ejection fraction. We investigated the prognostic impact of hyponatremia at discharge in patients with heart failure with preserved ejection fraction and its clinical characteristics.
Methods and results: The Japanese Heart Failure Syndrome with Preserved Ejection Fraction (JASPER) registry is a nationwide, observational, prospective registration of consecutive Japanese patients hospitalised with heart failure with preserved ejection fraction and left ventricular ejection fraction of 50% or greater. Five hundred consecutive patients were enrolled in this analysis. We divided the patients into two groups based on their sodium serum levels at discharge: hyponatremia group (sodium <135 mEq/L, n=50, 10.0%) and control group (sodium ⩾135 mEq/L, n=450, 90.0%). This present analysis had two primary endpoints: all-cause death and all-cause death or rehospitalisation for heart failure. At discharge, the hyponatremia group had lower systolic blood pressure (110.0 mmHg vs. 114.5 mmHg, P=0.014) and higher levels of urea nitrogen (31.9 mg/dL vs. 24.2 mg/dL, P=0.032). In the Kaplan-Meier analysis, more patients in the hyponatremia group reached the primary endpoints than those in the control group (log rank <0.01, respectively). In the Cox proportional hazard analysis, hyponatremia at discharge was a predictor of the two endpoints (all-cause death, hazard ratio 2.708, 95% confidence interval 1.557-4.708, P<0.001; all-cause death or rehospitalisation for heart failure, hazard ratio 1.829, 95% confidence interval 1.203-2.780, P=0.005).
Conclusions: Hyponatremia at discharge is associated with adverse prognosis in hospitalised patients with heart failure with preserved ejection fraction.
Keywords: Heart failure with preserved ejection fraction; hyponatremia; prognosis; sodium.